// SPDX-License-Identifier: GPL-2.0
/*
* PCI Peer 2 Peer DMA support.
*
* Copyright (c) 2016-2018, Logan Gunthorpe
* Copyright (c) 2016-2017, Microsemi Corporation
* Copyright (c) 2017, Christoph Hellwig
* Copyright (c) 2018, Eideticom Inc.
*/
#define pr_fmt(fmt) "pci-p2pdma: " fmt
#include <linux/ctype.h>
#include <linux/dma-map-ops.h>
#include <linux/pci-p2pdma.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/genalloc.h>
#include <linux/memremap.h>
#include <linux/percpu-refcount.h>
#include <linux/random.h>
#include <linux/seq_buf.h>
#include <linux/xarray.h>
struct pci_p2pdma {
struct gen_pool *pool;
bool p2pmem_published;
struct xarray map_types;
};
struct pci_p2pdma_pagemap {
struct pci_dev *provider;
u64 bus_offset;
struct dev_pagemap pgmap;
};
static struct pci_p2pdma_pagemap *to_p2p_pgmap(struct dev_pagemap *pgmap)
{
return container_of(pgmap, struct pci_p2pdma_pagemap, pgmap);
}
static ssize_t size_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct pci_dev *pdev = to_pci_dev(dev);
struct pci_p2pdma *p2pdma;
size_t size = 0;
rcu_read_lock();
p2pdma = rcu_dereference(pdev->p2pdma);
if (p2pdma && p2pdma->pool)
size = gen_pool_size(p2pdma->pool);
rcu_read_unlock();
return sysfs_emit(buf, "%zd\n", size);
}
static DEVICE_ATTR_RO(size);
static ssize_t available_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct pci_dev *pdev = to_pci_dev(dev);
struct pci_p2pdma *p2pdma;
size_t avail = 0;
rcu_read_lock();
p2pdma = rcu_dereference(pdev->p2pdma);
if (p2pdma && p2pdma->pool)
avail = gen_pool_avail(p2pdma->pool);
rcu_read_unlock();
return sysfs_emit(buf, "%zd\n", avail);
}
static DEVICE_ATTR_RO(available);
static ssize_t published_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct pci_dev *pdev = to_pci_dev(dev);
struct pci_p2pdma *p2pdma;
bool published = false;
rcu_read_lock();
p2pdma = rcu_dereference(pdev->p2pdma);
if (p2pdma)
published = p2pdma->p2pmem_published;
rcu_read_unlock();
return sysfs_emit(buf, "%d\n", published);
}
static DEVICE_ATTR_RO(published);
static int p2pmem_alloc_mmap(struct file *filp, struct kobject *kobj,
struct bin_attribute *attr, struct vm_area_struct *vma)
{
struct pci_dev *pdev = to_pci_dev(kobj_to_dev(kobj));
size_t len = vma->vm_end - vma->vm_start;
struct pci_p2pdma *p2pdma;
struct percpu_ref *ref;
unsigned long vaddr;
void *kaddr;
int ret;
/* prevent private mappings from being established */
if ((vma->vm_flags & VM_MAYSHARE) != VM_MAYSHARE) {
pci_info_ratelimited(pdev,
"%s: fail, attempted private mapping\n",
current->comm);
return -EINVAL;
}
if (vma->vm_pgoff) {
pci_info_ratelimited(pdev,
"%s: fail, attempted mapping with non-zero offset\n",
current->comm);
return -EINVAL;
}
rcu_read_lock();
p2pdma = rcu_dereference(pdev->p2pdma);
if (!p2pdma) {
ret = -ENODEV;
goto out;
}
kaddr = (void *)gen_pool_alloc_owner(p2pdma->pool, len, (void **)&ref);
if (!kaddr) {
ret = -ENOMEM;
goto out;
}
/*
* vm_insert_page() can sleep, so a reference is taken to mapping
* such that rcu_read_unlock() can be done before inserting the
* pages
*/
if (unlikely(!percpu_ref_tryget_live_rcu(ref))) {
ret = -ENODEV;
goto out_free_mem;
}
rcu_read_unlock();
for (vaddr = vma->vm_start; vaddr < vma->vm_end; vaddr += PAGE_SIZE) {
ret = vm_insert_page(vma, vaddr, virt_to_page(kaddr));
if (ret) {
gen_pool_free(p2pdma->pool, (uintptr_t)kaddr, len);
return ret;
}
percpu_ref_get(ref);
put_page(virt_to_page(kaddr));
kaddr += PAGE_SIZE;
len -= PAGE_SIZE;
}
percpu_ref_put(ref);
return 0;
out_free_mem:
gen_pool_free(p2pdma->pool, (uintptr_t)kaddr, len);
out:
rcu_read_unlock();
return ret;
}
static struct bin_attribute p2pmem_alloc_attr = {
.attr = { .name = "allocate", .mode = 0660 },
.mmap = p2pmem_alloc_mmap,
/*
* Some places where we want to call mmap (ie. python) will check
* that the file size is greater than the mmap size before allowing
* the mmap to continue. To work around this, just set the size
* to be very large.
*/
.size = SZ_1T,
};
static struct attribute *p2pmem_attrs[] = {
&dev_attr_size.attr,
&dev_attr_available.attr,
&dev_attr_published.attr,
NULL,
};
static struct bin_attribute *p2pmem_bin_attrs[] = {
&p2pmem_alloc_attr,
NULL,
};
static const struct attribute_group p2pmem_group = {
.attrs = p2pmem_attrs,
.bin_attrs = p2pmem_bin_attrs,
.name = "p2pmem",
};
static void p2pdma_page_free(struct page *page)
{
struct pci_p2pdma_pagemap *pgmap = to_p2p_pgmap(page->pgmap);
/* safe to dereference while a reference is held to the percpu ref */
struct pci_p2pdma *p2pdma =
rcu_dereference_protected(pgmap->provider->p2pdma, 1);
struct percpu_ref *ref;
gen_pool_free_owner(p2pdma->pool, (uintptr_t)page_to_virt(page),
PAGE_SIZE, (void **)&ref);
percpu_ref_put(ref);
}
static const struct dev_pagemap_ops p2pdma_pgmap_ops = {
.page_free = p2pdma_page_free,
};
static void pci_p2pdma_release(void *data)
{
struct pci_dev *pdev = data;
struct pci_p2pdma *p2pdma;
p2pdma = rcu_dereference_protected(pdev->p2pdma, 1);
if (!p2pdma)
return;
/* Flush and disable pci_alloc_p2p_mem() */
pdev->p2pdma = NULL;
synchronize_rcu();
gen_pool_destroy(p2pdma->pool);
sysfs_remove_group(&pdev->dev.kobj, &p2pmem_group);
xa_destroy(&p2pdma->map_types);
}
static int pci_p2pdma_setup(struct pci_dev *pdev)
{
int error = -ENOMEM;
struct pci_p2pdma *p2p;
p2p = devm_kzalloc(&pdev->dev, sizeof(*p2p), GFP_KERNEL);
if (!p2p)
return -ENOMEM;
xa_init(&p2p->map_types);
p2p->pool = gen_pool_create(PAGE_SHIFT, dev_to_node(&pdev->dev));
if (!p2p->pool)
goto out;
error = devm_add_action_or_reset(&pdev->dev, pci_p2pdma_release, pdev);
if (error)
goto out_pool_destroy;
error = sysfs_create_group(&pdev->dev.kobj, &p2pmem_group);
if (error)
goto out_pool_destroy;
rcu_assign_pointer(pdev->p2pdma, p2p);
return 0;
out_pool_destroy:
gen_pool_destroy(p2p->pool);
out:
devm_kfree(&pdev->dev, p2p);
return error;
}
static void pci_p2pdma_unmap_mappings(void *data)
{
struct pci_dev *pdev = data;
/*
* Removing the alloc attribute from sysfs will call
* unmap_mapping_range() on the inode, teardown any existing userspace
* mappings and prevent new ones from being created.
*/
sysfs_remove_file_from_group(&pdev->dev.kobj, &p2pmem_alloc_attr.attr,
p2pmem_group.name);
}
/**
* pci_p2pdma_add_resource - add memory for use as p2p memory
* @pdev: the device to add the memory to
* @bar: PCI BAR to add
* @size: size of the memory to add, may be zero to use the whole BAR
* @offset: offset into the PCI BAR
*
* The memory will be given ZONE_DEVICE struct pages so that it may
* be used with any DMA request.
*/
int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size,
u64 offset)
{
struct pci_p2pdma_pagemap *p2p_pgmap;
struct dev_pagemap *pgmap;
struct pci_p2pdma *p2pdma;
void *addr;
int error;
if (!(pci_resource_flags(pdev, bar) & IORESOURCE_MEM))
return -EINVAL;
if (offset >= pci_resource_len(pdev, bar))
return -EINVAL;
if (!size)
size = pci_resource_len(pdev, bar) - offset;
if (size + offset > pci_resource_len(pdev, bar))
return -EINVAL;
if (!pdev->p2pdma) {
error = pci_p2pdma_setup(pdev);
if (error)
return error;
}
p2p_pgmap = devm_kzalloc(&pdev->dev, sizeof(*p2p_pgmap), GFP_KERNEL);
if (!p2p_pgmap)
return -ENOMEM;
pgmap = &p2p_pgmap->pgmap;
pgmap->range.start = pci_resource_start(pdev, bar) + offset;
pgmap->range.end = pgmap->range.start + size - 1;
pgmap->nr_range = 1;
pgmap->type = MEMORY_DEVICE_PCI_P2PDMA;
pgmap->ops = &p2pdma_pgmap_ops;
p2p_pgmap->provider = pdev;
p2p_pgmap->bus_offset = pci_bus_address(pdev, bar) -
pci_resource_start(pdev, bar);
addr = devm_memremap_pages(&pdev->dev, pgmap);
if (IS_ERR(addr)) {
error = PTR_ERR(addr);
goto pgmap_free;
}
error = devm_add_action_or_reset(&pdev->dev, pci_p2pdma_unmap_mappings,
pdev);
if (error)
goto pages_free;
p2pdma = rcu_dereference_protected(pdev->p2pdma, 1);
error = gen_pool_add_owner(p2pdma->pool, (unsigned long)addr,
pci_bus_address(pdev, bar) + offset,
range_len(&pgmap->range), dev_to_node(&pdev->dev),
&pgmap->ref);
if (error)
goto pages_free;
pci_info(pdev, "added peer-to-peer DMA memory %#llx-%#llx\n",
pgmap->range.start, pgmap->range.end);
return 0;
pages_free:
devm_memunmap_pages(&pdev->dev, pgmap);
pgmap_free:
devm_kfree(&pdev->dev, pgmap);
return error;
}
EXPORT_SYMBOL_GPL(pci_p2pdma_add_resource);
/*
* Note this function returns the parent PCI device with a
* reference taken. It is the caller's responsibility to drop
* the reference.
*/
static struct pci_dev *find_parent_pci_dev(struct device *dev)
{
struct device *parent;
dev = get_device(dev);
while (dev) {
if (dev_is_pci(dev))
return to_pci_dev(dev);
parent = get_device(dev->parent);
put_device(dev);
dev = parent;
}
return NULL;
}
/*
* Check if a PCI bridge has its ACS redirection bits set to redirect P2P
* TLPs upstream via ACS. Returns 1 if the packets will be redirected
* upstream, 0 otherwise.
*/
static int pci_bridge_has_acs_redir(struct pci_dev *pdev)
{
int pos;
u16 ctrl;
pos = pdev->acs_cap;
if (!pos)
return 0;
pci_read_config_word(pdev, pos + PCI_ACS_CTRL, &ctrl);
if (ctrl & (PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_EC))
return 1;
return 0;
}
static void seq_buf_print_bus_devfn(struct seq_buf *buf, struct pci_dev *pdev)
{
if (!buf)
return;
seq_buf_printf(buf, "%s;", pci_name(pdev));
}
static bool cpu_supports_p2pdma(void)
{
#ifdef CONFIG_X86
struct cpuinfo_x86 *c = &cpu_data(0);
/* Any AMD CPU whose family ID is Zen or newer supports p2pdma */
if (c->x86_vendor == X86_VENDOR_AMD && c->x86 >= 0x17)
return true;
#endif
return false;
}
static const struct pci_p2pdma_whitelist_entry {
unsigned short vendor;
unsigned short device;
enum {
REQ_SAME_HOST_BRIDGE = 1 << 0,
} flags;
} pci_p2pdma_whitelist[] = {
/* Intel Xeon E5/Core i7 */
{PCI_VENDOR_ID_INTEL, 0x3c00, REQ_SAME_HOST_BRIDGE},
{PCI_VENDOR_ID_INTEL, 0x3c01, REQ_SAME_HOST_BRIDGE},
/* Intel Xeon E7 v3/Xeon E5 v3/Core i7 */
{PCI_VENDOR_ID_INTEL, 0x2f00, REQ_SAME_HOST_BRIDGE},
{PCI_VENDOR_ID_INTEL, 0x2f01, REQ_SAME_HOST_BRIDGE},
/* Intel Skylake-E */
{PCI_VENDOR_ID_INTEL, 0x2030, 0},
{PCI_VENDOR_ID_INTEL, 0x2031, 0},
{PCI_VENDOR_ID_INTEL, 0x2032, 0},
{PCI_VENDOR_ID_INTEL, 0x2033, 0},
{PCI_VENDOR_ID_INTEL, 0x2020, 0},
{PCI_VENDOR_ID_INTEL, 0x09a2, 0},
{}
};
/*
* If the first device on host's root bus is either devfn 00.0 or a PCIe
* Root Port, return it. Otherwise return NULL.
*
* We often use a devfn 00.0 "host bridge" in the pci_p2pdma_whitelist[]
* (though there is no PCI/PCIe requirement for such a device). On some
* platforms, e.g., Intel Skylake, there is no such host bridge device, and
* pci_p2pdma_whitelist[] may contain a Root Port at any devfn.
*
* This function is similar to pci_get_slot(host->bus, 0), but it does
* not take the pci_bus_sem lock since __host_bridge_whitelist() must not
* sleep.
*
* For this to be safe, the caller should hold a reference to a device on the
* bridge, which should ensure the host_bridge device will not be freed
* or removed from the head of the devices list.
*/
static struct pci_dev *pci_host_bridge_dev(struct pci_host_bridge *host)
{
struct pci_dev *root;
root = list_first_entry_or_null(&host->bus->devices,
struct pci_dev, bus_list);
if (!root)
return NULL;
if (root->devfn == PCI_DEVFN(0, 0))
return root;
if (pci_pcie_type(root) == PCI_EXP_TYPE_ROOT_PORT)
return root;
return NULL;
}
static bool __host_bridge_whitelist(struct pci_host_bridge *host,
bool same_host_bridge, bool warn)
{
struct pci_dev *root = pci_host_bridge_dev(host);
const struct pci_p2pdma_whitelist_entry *entry;
unsigned short vendor, device;
if (!root)
return false;
vendor = root->vendor;
device = root->device;
for (entry = pci_p2pdma_whitelist; entry->vendor; entry++) {
if (vendor != entry->vendor || device != entry->device)
continue;
if (entry->flags & REQ_SAME_HOST_BRIDGE && !same_host_bridge)
return false;
return true;
}
if (warn)
pci_warn(root, "Host bridge not in P2PDMA whitelist: %04x:%04x\n",
vendor, device);
return false;
}
/*
* If we can't find a common upstream bridge take a look at the root
* complex and compare it to a whitelist of known good hardware.
*/
static bool host_bridge_whitelist(struct pci_dev *a, struct pci_dev *b,
bool warn)
{
struct pci_host_bridge *host_a = pci_find_host_bridge(a->bus);
struct pci_host_bridge *host_b = pci_find_host_bridge(b->bus);
if (host_a == host_b)
return __host_bridge_whitelist(host_a, true, warn);
if (__host_bridge_whitelist(host_a, false, warn) &&
__host_bridge_whitelist(host_b, false, warn))
return true;
return false;
}
static unsigned long map_types_idx(struct pci_dev *client)
{
return (pci_domain_nr(client->bus) << 16) | pci_dev_id(client);
}
/*
* Calculate the P2PDMA mapping type and distance between two PCI devices.
*
* If the two devices are the same PCI function, return
* PCI_P2PDMA_MAP_BUS_ADDR and a distance of 0.
*
* If they are two functions of the same device, return
* PCI_P2PDMA_MAP_BUS_ADDR and a distance of 2 (one hop up to the bridge,
* then one hop back down to another function of the same device).
*
* In the case where two devices are connected to the same PCIe switch,
* return a distance of 4. This corresponds to the following PCI tree:
*
* -+ Root Port
* \+ Switch Upstream Port
* +-+ Switch Downstream Port 0
* + \- Device A
* \-+ Switch Downstream Port 1
* \- Device B
*
* The distance is 4 because we traverse from Device A to Downstream Port 0
* to the common Switch Upstream Port, back down to Downstream Port 1 and
* then to Device B. The mapping type returned depends on the ACS
* redirection setting of the ports along the path.
*
* If ACS redirect is set on any port in the path, traffic between the
* devices will go through the host bridge, so return
* PCI_P2PDMA_MAP_THRU_HOST_BRIDGE; otherwise return
* PCI_P2PDMA_MAP_BUS_ADDR.
*
* Any two devices that have a data path that goes through the host bridge
* will consult a whitelist. If the host bridge is in the whitelist, return
* PCI_P2PDMA_MAP_THRU_HOST_BRIDGE with the distance set to the number of
* ports per above. If the device is not in the whitelist, return
* PCI_P2PDMA_MAP_NOT_SUPPORTED.
*/
static enum pci_p2pdma_map_type
calc_map_type_and_dist(struct pci_dev *provider, struct pci_dev *client,
int *dist, bool verbose)
{
enum pci_p2pdma_map_type map_type = PCI_P2PDMA_MAP_THRU_HOST_BRIDGE;
struct pci_dev *a = provider, *b = client, *bb;
bool acs_redirects = false;
struct pci_p2pdma *p2pdma;
struct seq_buf acs_list;
int acs_cnt = 0;
int dist_a = 0;
int dist_b = 0;
char buf[128];
seq_buf_init(&acs_list, buf, sizeof(buf));
/*
* Note, we don't need to take references to devices returned by
* pci_upstream_bridge() seeing we hold a reference to a child
* device which will already hold a reference to the upstream bridge.
*/
while (a) {
dist_b = 0;
if (pci_bridge_has_acs_redir(a)) {
seq_buf_print_bus_devfn(&acs_list, a);
acs_cnt++;
}
bb = b;
while (bb) {
if (a == bb)
goto check_b_path_acs;
bb = pci_upstream_bridge(bb);
dist_b++;
}
a = pci_upstream_bridge(a);
dist_a++;
}
*dist = dist_a + dist_b;
goto map_through_host_bridge;
check_b_path_acs:
bb = b;
while (bb) {
if (a == bb)
break;
if (pci_bridge_has_acs_redir(bb)) {
seq_buf_print_bus_devfn(&acs_list, bb);
acs_cnt++;
}
bb = pci_upstream_bridge(bb);
}
*dist = dist_a + dist_b;
if (!acs_cnt) {
map_type = PCI_P2PDMA_MAP_BUS_ADDR;
goto done;
}
if (verbose) {
acs_list.buffer[acs_list.len-1] = 0; /* drop final semicolon */
pci_warn(client, "ACS redirect is set between the client and provider (%s)\n",
pci_name(provider));
pci_warn(client, "to disable ACS redirect for this path, add the kernel parameter: pci=disable_acs_redir=%s\n",
acs_list.buffer);
}
acs_redirects = true;
map_through_host_bridge:
if (!cpu_supports_p2pdma() &&
!host_bridge_whitelist(provider, client, acs_redirects)) {
if (verbose)
pci_warn(client, "cannot be used for peer-to-peer DMA as the client and provider (%s) do not share an upstream bridge or whitelisted host bridge\n",
pci_name(provider));
map_type = PCI_P2PDMA_MAP_NOT_SUPPORTED;
}
done:
rcu_read_lock();
p2pdma = rcu_dereference(provider->p2pdma);
if (p2pdma)
xa_store(&p2pdma->map_types, map_types_idx(client),
xa_mk_value(map_type), GFP_ATOMIC);
rcu_read_unlock();
return map_type;
}
/**
* pci_p2pdma_distance_many - Determine the cumulative distance between
* a p2pdma provider and the clients in use.
* @provider: p2pdma provider to check against the client list
* @clients: array of devices to check (NULL-terminated)
* @num_clients: number of clients in the array
* @verbose: if true, print warnings for devices when we return -1
*
* Returns -1 if any of the clients are not compatible, otherwise returns a
* positive number where a lower number is the preferable choice. (If there's
* one client that's the same as the provider it will return 0, which is best
* choice).
*
* "compatible" means the provider and the clients are either all behind
* the same PCI root port or the host bridges connected to each of the devices
* are listed in the 'pci_p2pdma_whitelist'.
*/
int pci_p2pdma_distance_many(struct pci_dev *provider, struct device **clients,
int num_clients, bool verbose)
{
enum pci_p2pdma_map_type map;
bool not_supported = false;
struct pci_dev *pci_client;
int total_dist = 0;
int i, distance;
if (num_clients == 0)
return -1;
for (i = 0; i < num_clients; i++) {
pci_client = find_parent_pci_dev(clients[i]);
if (!pci_client) {
if (verbose)
dev_warn(clients[i],
"cannot be used for peer-to-peer DMA as it is not a PCI device\n");
return -1;
}
map = calc_map_type_and_dist(provider, pci_client, &distance,
verbose);
pci_dev_put(pci_client);
if (map == PCI_P2PDMA_MAP_NOT_SUPPORTED)
not_supported = true;
if (not_supported && !verbose)
break;
total_dist += distance;
}
if (not_supported)
return -1;
return total_dist;
}
EXPORT_SYMBOL_GPL(pci_p2pdma_distance_many);
/**
* pci_has_p2pmem - check if a given PCI device has published any p2pmem
* @pdev: PCI device to check
*/
bool pci_has_p2pmem(struct pci_dev *pdev)
{
struct pci_p2pdma *p2pdma;
bool res;
rcu_read_lock();
p2pdma = rcu_dereference(pdev->p2pdma);
res = p2pdma && p2pdma->p2pmem_published;
rcu_read_unlock();
return res;
}
EXPORT_SYMBOL_GPL(pci_has_p2pmem);
/**
* pci_p2pmem_find_many - find a peer-to-peer DMA memory device compatible with
* the specified list of clients and shortest distance
* @clients: array of devices to check (NULL-terminated)
* @num_clients: number of client devices in the list
*
* If multiple devices are behind the same switch, the one "closest" to the
* client devices in use will be chosen first. (So if one of the providers is
* the same as one of the clients, that provider will be used ahead of any
* other providers that are unrelated). If multiple providers are an equal
* distance away, one will be chosen at random.
*
* Returns a pointer to the PCI device with a reference taken (use pci_dev_put
* to return the reference) or NULL if no compatible device is found. The
* found provider will also be assigned to the client list.
*/
struct pci_dev *pci_p2pmem_find_many(struct device **clients, int num_clients)
{
struct pci_dev *pdev = NULL;
int distance;
int closest_distance = INT_MAX;
struct pci_dev **closest_pdevs;
int dev_cnt = 0;
const int max_devs = PAGE_SIZE / sizeof(*closest_pdevs);
int i;
closest_pdevs = kmalloc(PAGE_SIZE, GFP_KERNEL);
if (!closest_pdevs)
return NULL;
for_each_pci_dev(pdev) {
if (!pci_has_p2pmem(pdev))
continue;
distance = pci_p2pdma_distance_many(pdev, clients,
num_clients, false);
if (distance < 0 || distance > closest_distance)
continue;
if (distance == closest_distance && dev_cnt >= max_devs)
continue;
if (distance < closest_distance) {
for (i = 0; i < dev_cnt; i++)
pci_dev_put(closest_pdevs[i]);
dev_cnt = 0;
closest_distance = distance;
}
closest_pdevs[dev_cnt++] = pci_dev_get(pdev);
}
if (dev_cnt)
pdev = pci_dev_get(closest_pdevs[get_random_u32_below(dev_cnt)]);
for (i = 0; i < dev_cnt; i++)
pci_dev_put(closest_pdevs[i]);
kfree(closest_pdevs);
return pdev;
}
EXPORT_SYMBOL_GPL(pci_p2pmem_find_many);
/**
* pci_alloc_p2pmem - allocate peer-to-peer DMA memory
* @pdev: the device to allocate memory from
* @size: number of bytes to allocate
*
* Returns the allocated memory or NULL on error.
*/
void *pci_alloc_p2pmem(struct pci_dev *pdev, size_t size)
{
void *ret = NULL;
struct percpu_ref *ref;
struct pci_p2pdma *p2pdma;
/*
* Pairs with synchronize_rcu() in pci_p2pdma_release() to
* ensure pdev->p2pdma is non-NULL for the duration of the
* read-lock.
*/
rcu_read_lock();
p2pdma = rcu_dereference(pdev->p2pdma);
if (unlikely(!p2pdma))
goto out;
ret = (void *)gen_pool_alloc_owner(p2pdma->pool, size, (void **) &ref);
if (!ret)
goto out;
if (unlikely(!percpu_ref_tryget_live_rcu(ref))) {
gen_pool_free(p2pdma->pool, (unsigned long) ret, size);
ret = NULL;
}
out:
rcu_read_unlock();
return ret;
}
EXPORT_SYMBOL_GPL(pci_alloc_p2pmem);
/**
* pci_free_p2pmem - free peer-to-peer DMA memory
* @pdev: the device the memory was allocated from
* @addr: address of the memory that was allocated
* @size: number of bytes that were allocated
*/
void pci_free_p2pmem(struct pci_dev *pdev, void *addr, size_t size)
{
struct percpu_ref *ref;
struct pci_p2pdma *p2pdma = rcu_dereference_protected(pdev->p2pdma, 1);
gen_pool_free_owner(p2pdma->pool, (uintptr_t)addr, size,
(void **) &ref);
percpu_ref_put(ref);
}
EXPORT_SYMBOL_GPL(pci_free_p2pmem);
/**
* pci_p2pmem_virt_to_bus - return the PCI bus address for a given virtual
* address obtained with pci_alloc_p2pmem()
* @pdev: the device the memory was allocated from
* @addr: address of the memory that was allocated
*/
pci_bus_addr_t pci_p2pmem_virt_to_bus(struct pci_dev *pdev, void *addr)
{
struct pci_p2pdma *p2pdma;
if (!addr)
return 0;
p2pdma = rcu_dereference_protected(pdev->p2pdma, 1);
if (!p2pdma)
return 0;
/*
* Note: when we added the memory to the pool we used the PCI
* bus address as the physical address. So gen_pool_virt_to_phys()
* actually returns the bus address despite the misleading name.
*/
return gen_pool_virt_to_phys(p2pdma->pool, (unsigned long)addr);
}
EXPORT_SYMBOL_GPL(pci_p2pmem_virt_to_bus);
/**
* pci_p2pmem_alloc_sgl - allocate peer-to-peer DMA memory in a scatterlist
* @pdev: the device to allocate memory from
* @nents: the number of SG entries in the list
* @length: number of bytes to allocate
*
* Return: %NULL on error or &struct scatterlist pointer and @nents on success
*/
struct scatterlist *pci_p2pmem_alloc_sgl(struct pci_dev *pdev,
unsigned int *nents, u32 length)
{
struct scatterlist *sg;
void *addr;
sg = kmalloc(sizeof(*sg), GFP_KERNEL);
if (!sg)
return NULL;
sg_init_table(sg, 1);
addr = pci_alloc_p2pmem(pdev, length);
if (!addr)
goto out_free_sg;
sg_set_buf(sg, addr, length);
*nents = 1;
return sg;
out_free_sg:
kfree(sg);
return NULL;
}
EXPORT_SYMBOL_GPL(pci_p2pmem_alloc_sgl);
/**
* pci_p2pmem_free_sgl - free a scatterlist allocated by pci_p2pmem_alloc_sgl()
* @pdev: the device to allocate memory from
* @sgl: the allocated scatterlist
*/
void pci_p2pmem_free_sgl(struct pci_dev *pdev, struct scatterlist *sgl)
{
struct scatterlist *sg;
int count;
for_each_sg(sgl, sg, INT_MAX, count) {
if (!sg)
break;
pci_free_p2pmem(pdev, sg_virt(sg), sg->length);
}
kfree(sgl);
}
EXPORT_SYMBOL_GPL(pci_p2pmem_free_sgl);
/**
* pci_p2pmem_publish - publish the peer-to-peer DMA memory for use by
* other devices with pci_p2pmem_find()
* @pdev: the device with peer-to-peer DMA memory to publish
* @publish: set to true to publish the memory, false to unpublish it
*
* Published memory can be used by other PCI device drivers for
* peer-2-peer DMA operations. Non-published memory is reserved for
* exclusive use of the device driver that registers the peer-to-peer
* memory.
*/
void pci_p2pmem_publish(struct pci_dev *pdev, bool publish)
{
struct pci_p2pdma *p2pdma;
rcu_read_lock();
p2pdma = rcu_dereference(pdev->p2pdma);
if (p2pdma)
p2pdma->p2pmem_published = publish;
rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(pci_p2pmem_publish);
static enum pci_p2pdma_map_type pci_p2pdma_map_type(struct dev_pagemap *pgmap,
struct device *dev)
{
enum pci_p2pdma_map_type type = PCI_P2PDMA_MAP_NOT_SUPPORTED;
struct pci_dev *provider = to_p2p_pgmap(pgmap)->provider;
struct pci_dev *client;
struct pci_p2pdma *p2pdma;
int dist;
if (!provider->p2pdma)
return PCI_P2PDMA_MAP_NOT_SUPPORTED;
if (!dev_is_pci(dev))
return PCI_P2PDMA_MAP_NOT_SUPPORTED;
client = to_pci_dev(dev);
rcu_read_lock();
p2pdma = rcu_dereference(provider->p2pdma);
if (p2pdma)
type = xa_to_value(xa_load(&p2pdma->map_types,
map_types_idx(client)));
rcu_read_unlock();
if (type == PCI_P2PDMA_MAP_UNKNOWN)
return calc_map_type_and_dist(provider, client, &dist, true);
return type;
}
/**
* pci_p2pdma_map_segment - map an sg segment determining the mapping type
* @state: State structure that should be declared outside of the for_each_sg()
* loop and initialized to zero.
* @dev: DMA device that's doing the mapping operation
* @sg: scatterlist segment to map
*
* This is a helper to be used by non-IOMMU dma_map_sg() implementations where
* the sg segment is the same for the page_link and the dma_address.
*
* Attempt to map a single segment in an SGL with the PCI bus address.
* The segment must point to a PCI P2PDMA page and thus must be
* wrapped in a is_pci_p2pdma_page(sg_page(sg)) check.
*
* Returns the type of mapping used and maps the page if the type is
* PCI_P2PDMA_MAP_BUS_ADDR.
*/
enum pci_p2pdma_map_type
pci_p2pdma_map_segment(struct pci_p2pdma_map_state *state, struct device *dev,
struct scatterlist *sg)
{
if (state->pgmap != sg_page(sg)->pgmap) {
state->pgmap = sg_page(sg)->pgmap;
state->map = pci_p2pdma_map_type(state->pgmap, dev);
state->bus_off = to_p2p_pgmap(state->pgmap)->bus_offset;
}
if (state->map == PCI_P2PDMA_MAP_BUS_ADDR) {
sg->dma_address = sg_phys(sg) + state->bus_off;
sg_dma_len(sg) = sg->length;
sg_dma_mark_bus_address(sg);
}
return state->map;
}
/**
* pci_p2pdma_enable_store - parse a configfs/sysfs attribute store
* to enable p2pdma
* @page: contents of the value to be stored
* @p2p_dev: returns the PCI device that was selected to be used
* (if one was specified in the stored value)
* @use_p2pdma: returns whether to enable p2pdma or not
*
* Parses an attribute value to decide whether to enable p2pdma.
* The value can select a PCI device (using its full BDF device
* name) or a boolean (in any format kstrtobool() accepts). A false
* value disables p2pdma, a true value expects the caller
* to automatically find a compatible device and specifying a PCI device
* expects the caller to use the specific provider.
*
* pci_p2pdma_enable_show() should be used as the show operation for
* the attribute.
*
* Returns 0 on success
*/
int pci_p2pdma_enable_store(const char *page, struct pci_dev **p2p_dev,
bool *use_p2pdma)
{
struct device *dev;
dev = bus_find_device_by_name(&pci_bus_type, NULL, page);
if (dev) {
*use_p2pdma = true;
*p2p_dev = to_pci_dev(dev);
if (!pci_has_p2pmem(*p2p_dev)) {
pci_err(*p2p_dev,
"PCI device has no peer-to-peer memory: %s\n",
page);
pci_dev_put(*p2p_dev);
return -ENODEV;
}
return 0;
} else if ((page[0] == '0' || page[0] == '1') && !iscntrl(page[1])) {
/*
* If the user enters a PCI device that doesn't exist
* like "0000:01:00.1", we don't want kstrtobool to think
* it's a '0' when it's clearly not what the user wanted.
* So we require 0's and 1's to be exactly one character.
*/
} else if (!kstrtobool(page, use_p2pdma)) {
return 0;
}
pr_err("No such PCI device: %.*s\n", (int)strcspn(page, "\n"), page);
return -ENODEV;
}
EXPORT_SYMBOL_GPL(pci_p2pdma_enable_store);
/**
* pci_p2pdma_enable_show - show a configfs/sysfs attribute indicating
* whether p2pdma is enabled
* @page: contents of the stored value
* @p2p_dev: the selected p2p device (NULL if no device is selected)
* @use_p2pdma: whether p2pdma has been enabled
*
* Attributes that use pci_p2pdma_enable_store() should use this function
* to show the value of the attribute.
*
* Returns 0 on success
*/
ssize_t pci_p2pdma_enable_show(char *page, struct pci_dev *p2p_dev,
bool use_p2pdma)
{
if (!use_p2pdma)
return sprintf(page, "0\n");
if (!p2p_dev)
return sprintf(page, "1\n");
return sprintf(page, "%s\n", pci_name(p2p_dev));
}
EXPORT_SYMBOL_GPL(pci_p2pdma_enable_show);
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